/D=5 simple supergravity on AdS3×S2 and /N=4 superconformal field theory

We study the Kaluza-Klein spectrum of D=5 simple supergravity on S² with special interest in the relation to a two-dimensional N=4 superconformal field theory. The spectrum is obtained around the maximally supersymmetric Freund-Rubin-like background AdS₃× S² by closely following the well-known techniques developed in D=11 supergravity. All the vector excitations turn out to be "(anti-)self-dual", having only one dynamical degree of freedom. The representation theory for the Lie superalgebra SU(1,1|2) is developed by means of the oscillator method. We calculate the conformal weight of the boundary operator by estimating the asymptotic behavior of the wave function for each Kaluza-Klein mode. All the towers of particles are shown to fall into four infinite series of chiral primary representations of SU(1,1|2)× SL(2, R) (direct product), or OSp(2,2|2;-1)≅ SU(1,1|2)× SL(2, R) (semi-direct product).